Bingo.
I'm glad someone got to this before I had the time to reply. It's not either or. It's both and.
Number one, we are presented with theologically loaded words in the Bible like: propitiation, justification, etc. The jargon is both legal and often financial in explaining what Christ did for us. They all lead to the idea that Christ paid for our sins in full, one version probably oversimplifies it to "made right" in the sight of God, but you get the idea. There is no other down payment or last payment payoff to be made. That clearly means there are no set rewards for working towards salvation. We do not earn our salvation by doing good things.
Ephesians 2:8-9 HCSB
For you are saved by grace through faith, and this is not from yourselves; it is God's gift- not from works, so that no one can boast.
However, on a similar and related note, we don't run the other way and say there are no rules to being a Christian. I truly believe that a Christian undergoes a life-long process of Jesus transforming them into some more and something better. That doesn't mean life's gonna be easy and get better. There will be failure, there will be slip-ups, but you are a child of God. A child of God does not live the life of the world. It's not at all about following rules, it's about the change at the core - deep in the soul or heart.
II Corinthians 3:18 HCSB
We all, with unveiled faces, are looking as in a mirror at the glory of the Lord and are being transformed into the same image from glory to glory; this is from the Lord who is the Spirit.